Effects of temperature on the photosynthesis–irradiance response curves of newly matured leaves of alfalfa

1977 ◽  
Vol 55 (8) ◽  
pp. 872-879 ◽  
Author(s):  
S. B. Ku ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Response Curves ◽  
Oxygen Inhibition ◽  
Thermal Environments ◽  
Growth Regime ◽  
Medicago Sativa L ◽  
Effects Of Temperature ◽  
Mesophyll Resistance

Various carbon dioxide exchange characteristics are described for two alfalfa (Medicago sativa L.) genotypes (AT 171 and CC 120) grown at 20:15 °C and 30:25 °C day:night temperatures and 53 nE cm−2 s−1 irradiance (400–700 nm). Growth at 30:25 °C as compared with 20:15 °C resulted in lower net carbon dioxide exchange rates (NCE) for both genotypes when analyzed at 20 °C, but did not cause any sizeable change for CC 120 at 30 °C. Oxygen inhibition of photosynthesis increased with irradiance to 48 nE cm−2 s−1 but either declined or remained constant with further increase in irradiance. Oxygen inhibition was higher at 30 °C than at 20 °C and was not consistently influenced by growth temperature. However, the ratio of oxygen inhibition to carbon dioxide exchange rate in air containing 1% oxygen and the mesophyll resistance were greater with AT 171 grown at 30:25 °C than at 20:15 °C, particularly at high irradiances. NCE measured at 20 °C instead of 30 °C for plants grown at 30:25 °C was reduced to a much more marked extent with CC 120 than with AT 171; this difference was paralleled by a more marked increase in stomatal resistance length (rSL) for CC 120.rSL decreased with an increase in irradiance, was generally higher at 20 °C than at 30 °C, and did not differ between growth temperatures when measured at an irradiance of 116 nE cm−2 s−1 and a temperature equal to the day temperature of the growth regime. The results are discussed in relation to factors responsible for adaptability to different thermal environments.

Effects of temperature on the morphology and photosynthetic activity of newly matured leaves of alfalfa

1973 ◽  
Vol 51 (10) ◽  
pp. 1907-1916 ◽  
Author(s):  
S. B. Ku ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Exchange Rate ◽  
Water Content ◽  
Intercellular Space ◽  
Leaf Water Content ◽  
Carbon Dioxide Exchange ◽  
Specific Leaf Weight ◽  
Leaf Density ◽  
Effects Of Temperature ◽  
Space Volume

Effects of temperature on (1) physical characteristics of newly matured leaves throughout regrowth, and (2) net carbon dioxide exchange–irradiance response curves throughout regrowth and throughout the day are described for two alfalfa (Medicago saliva L.) genotypes (AT171 and CC120) grown at 20/15C and 30/25C day/night temperatures and 53 nE cm−2 s−1 irradiance (400–700 nm).Area per leaf increased linearly with increasing leaf number up to the fourth or fifth leaf, and thereafter remained constant. Both specific leaf weight and leaf density were constant for the first four leaves, and increased sharply thereafter, particularly at day/night temperatures of 20/15C. Percentage of leaf water content did not change throughout regrowth at 30/25C, but decreased after leaf 4 at 20/15C. Intercellular space volume fluctuated with leaf number. Leaf area was larger, specific leaf weight, and leaf density were greater, intercellular space volume was higher, and percentage of leaf water content was lower, with plants grown at 20/15C than at 30/25C.The net carbon dioxide exchange rate at 116 nE cm−2 s−1 increased with leaves produced progressively until a peak was reached at leaf 4 or 5 and then decreased. At any given leaf position, net carbon dioxide exchange rate at 116 nE cm−2 s−1 was greater at 20/15C than at 30/25C for AT171, but was the same at both temperatures for CC120. In contrast, net carbon dioxide exchange rate at 76 nE cm−2 s−1 was greater at 20/15C than 30/25C for both genotypes. Net carbon dioxide exchange rates measured in the morning were always lower than those measured in the afternoon regardless of irradiance, genotype, and growth temperature.

Differential Gas Exchange Responses of Two Biotypes of Redroot Pigweed to Atrazine

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 68-72 ◽  
Author(s):  
L. D. West ◽  
T. J. Muzik ◽  
R. E. Witters
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Photosynthetic Activity ◽  
Guard Cells ◽  
Stomatal Resistance ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Mesophyll Tissue ◽  
Diffusive Resistance ◽  
Mesophyll Resistance

Differences were shown to exist in photosynthetic rate, transpiration rate, and carbon dioxide leaf diffusive resistance between atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] susceptible (S) and resistant (R) plants of redroot pigweed (Amaranthus retroflexusL.). Chlorbromuron [3-(4-bromo-3-chlorophenyl)-1-methoxy-1-methylurea] and diruon [3-(3,4-dichlorophenyl)-1,1-dimethylurea] were the only herbicides tested that controlled both biotypes, but all of the herbicides except norea [3-(hexahydro-4,7-methanoindan-5-yl)-1,1-dimethylurea] controlled the S biotype. Although photosynthetic activity and transpiration were reduced in both biotypes by atrazine at 50 and 70 ppm, the decline was much greater in the S biotype than in the R biotype and persisted a longer time in the S biotype. Leaf CO2diffusive resistances of the biotypes were increased by atrazine applications. Mesophyll resistance was increased to a greater extent than stomatal resistance suggesting that reduction of photosynthesis is due to a greater effect of atrazine on the mesophyll tissue than on the guard cells.

Effect of Water Deficit on Carbon Dioxide Exchange and Leaf Elongation Rate of Panicum maximum Var. trichoglume

1976 ◽  
Vol 3 (3) ◽  
pp. 401 ◽  
Author(s):  
MM Ludlow ◽  
TT Ng
Keyword(s):  
Carbon Dioxide ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Net Photosynthesis ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Carbon Dioxide Exchange ◽  
Leaf Elongation ◽  
Water Deficits ◽  
Water Potentials

The responses of carbon dioxide exchange and leaf elongation of potted P. maximum var. trichoglume plants to water deficits were investigated in controlled environments and outdoors during drying cycles down to -92 bars leaf water potential, The sensitivities of net photosynthesis and leaf elongation to water deficits were similar. The leaf water potentials at which net photosynthesis and elongation ceased (c. -12 bars), and stomatal resistance increased substantially (- 6 bars), were relatively unaffected by nitrogen supply, environmental conditions during growth, and whether plants had previously experienced stress. However, these factors influenced the rate of net photosynthesis, at high leaf water potentials by affecting stomatal resistance and at moderate water potentials by affecting both stomatal and intracellular resistances. Stomata1 resistance was more sensitive than intracellular resistance to water deficits. Dark respiration rate decreased with leaf water potential, and was higher in plants receiving additional nitrogen. At moderate leaf water potentials (-7 to -9 bars), net photosynthesis of this C4 grass exhibited light saturation and rates similar to C3 plants. We suggest that the difference in behaviour of controlled-environment-grown and field-grown plants to water deficits observed with some species is unlikely to be due to differences in the aerial environment, but may result from differences in the rate at which stress develops. The ecological significance and evolution of the C4 syndrome are discussed briefly.

The Photosynthesis and Transpiration of Crops

1966 ◽  
Vol 2 (1) ◽  
pp. 1-14 ◽  
Author(s):  
J. L. Monteith
Keyword(s):  
Carbon Dioxide ◽  
Radiant Energy ◽  
Visible Spectrum ◽  
Moisture Stress ◽  
Incident Radiation ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Gross Photosynthesis ◽  
Production Ratio ◽  
Potential Rate

SummaryWhen a leaf absorbs radiant energy, only a small fraction is stored chemically in photosynthesis. In sunlight, this fraction is at most one-fifth of the energy in the visible spectrum, decreasing with increasing light intensity because of the finite resistance to the diffusion of carbon dioxide through the leaf to the chloroplasts. Energy absorbed but not stored in photosynthesis is dissipated by transpiration and convection.The potential or maximum photosynthesis of a crop canopy can be estimated from a set of six parameters describing the photosynthesis-light curve of single leaves, the arrangement of leaves in the canopy, and radiation climate. Comparing estimates of potential photosynthesis with measurements of carbon dioxide exchange over a field of sugar beet, the estimated rate of respiration was 2 gm carbohydrate per m2 leaf area per day, equivalent to 44 per cent of gross photosynthesis over the whole growing season. Over the season, the foliage lost 34 per cent of incident radiation by transmission to the soil.The potential rate of transpiration can be found from Penman's formula assuming values of external (aerodynamic) and internal (mainly stomatal) resistance for the canopy as a whole. In south-east England, the energy for potential transpiration is almost equal to net heat H in summer and is therefore about half the energy of incoming solar radiation. For a real crop of grass subject to moisture stress, transpiration was less than the potential rate at about 0·8 H on average and 0·3 H in very dry weather.During the summer, cumulative photosynthesis increases linearly with cumulative transpiration to give a production ratio (gross photosynthesis/transpiration) of 1/100 in the Thames Valley and 1/200 in the Sacramento Valley. The production ratio is expected to change with crop type as well as with climate.

COMPARISON OF PHOTOSYNTHESIS IN NORMAL AND TRIAZINE-RESISTANT Brassica

1987 ◽  
Vol 67 (2) ◽  
pp. 457-466 ◽  
Author(s):  
S. L. A. HOBBS
Keyword(s):  
Carbon Dioxide ◽  
Exchange Rate ◽  
Chlorophyll A ◽  
Dry Weight ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Shoot Dry Weight ◽  
Significant Difference ◽  
The Difference ◽  
Net Assimilation

In spaced field plantings, triazine-resistant types of Brassica campestris L. and B. napus L. had a carbon dioxide exchange rate (CER) 28% lower in 1983 and 25% lower in 1984 than normal (triazine-susceptible) types. In plots simulating agronomic spacings in 1984, the difference between CER in normal and resistant types was 17% for B. campestris, 14% for B. napus and 13% for B. juncea L. Differences were apparent throughout the season and were not associated with any particular stage of growth. Resistant progeny from reciprocal crosses between resistant and susceptible plants of B. napus exhibited reduced CER at all levels of photosynthetically active radiation and at all temperatures. There was no significant difference between plant types for chlorophyll a + b content or chlorophyll a/b ratio. Shoot dry weight, stomatal resistance and specific leaf weight were higher in the normal types, but there was no difference between types in either relative growth rate or net assimilation rate. The reduced biomass was not therefore linked to reduced CER.Key words: Carbon dioxide exchange rate, herbicide, oilseed, rapeseed

RELATIONSHIPS BETWEEN CARBON DIOXIDE EXCHANGE RATE, PHOTOSYNTHETIC AREA AND BIOMASS IN PEA

1986 ◽  
Vol 66 (3) ◽  
pp. 465-472 ◽  
Author(s):  
S. L. A. HOBBS
Keyword(s):  
Carbon Dioxide ◽  
Exchange Rate ◽  
Pisum Sativum ◽  
Chlorophyll Content ◽  
Substantial Reduction ◽  
Dry Weight ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Shoot Dry Weight ◽  
Pisum Sativum L

Compensation between carbon dioxide exchange rate per unit photosynthetic area (CER) and total photosynthetic area (TPA) of a plant was examined in field-grown pea (Pisum sativum L.). Eight near-isogenic lines of cv. Alaska, representing all possible phenotypes of the genes af (leaflets transformed to tendrils), st (reduced stipule area) and tl (tendrils transformed to leaflets), were examined. The CER was measured on the leaflets (AfAf), tendrils (afafTlTl) or minute leaflets (afaftltl). The TPA was significantly reduced by the st gene in AfAf types (normal leaflets) with an apparently associated increase in CER. The st gene also significantly reduced the TPA in afaf types but there was no associated increase in CER. Tendrils had a lower CER than normal leaflets and comprised 22% of the TPA of the semi-leafless (afafStStTlTl) type. Crosses were made between a semi-leafless pea and four normal-leafed types previously selected for high or low CER. The CER means (normal leaflets) of the F1 progeny showed variability which was related to parental values. This was also true for the CER means (tendrils) of the populations of semi-leafless F2 segregants showing that genetic variability for CER can exist in tendrils. In the F2, tendril CER was correlated negatively to stomatal resistance and positively to chlorophyll content and final shoot dry weight (biomass). Genetic improvement in CER may be important when a plant ideotype requires substantial reduction in TPA.Key words: Photosynthesis, pea, chlorophyll content, stomatal resistance, Pisum sativum

Mesophyll resistance to photosynthetic carbon dioxide uptake in leaves: dependence upon stomatal aperture

1984 ◽  
Vol 62 (1) ◽  
pp. 163-165 ◽  
Author(s):  
David F. Parkhurst
Keyword(s):  
Differential Equation ◽  
Carbon Dioxide ◽  
Partial Differential Equation ◽  
Chemical Reaction ◽  
Stomatal Resistance ◽  
Stomatal Aperture ◽  
Plant Leaves ◽  
Carbon Dioxide Uptake ◽  
Photosynthetic Carbon ◽  
Mesophyll Resistance

A model for carbon dioxide uptake by plant leaves, based on the partial differential equation for diffusion with chemical reaction, is used to simulate photosynthesis for various stomatal openings. The results show that not only the "stomatal resistance" but also the commonly calculated "mesophyll resistance" varies when nothing but stomatal aperture is changed. Simplistic uses of the resistance concept (or related conductances) may be more misleading than useful for modelling photosynthesis, because the various resistance components are neither independent nor additive.

Photosynthesis and Carbon Dioxide Transfer Resistance of Lodgepole Pine Seedlings in Relation to Irradiance, Temperature, and Water Potential

1974 ◽  
Vol 4 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Gary F. Dykstra
Keyword(s):  
Carbon Dioxide ◽  
Water Potential ◽  
Environmental Conditions ◽  
Net Photosynthesis ◽  
Stomatal Resistance ◽  
Transfer Resistance ◽  
Pine Seedlings ◽  
Rate Limiting ◽  
Potential Maximum ◽  
Mesophyll Resistance

Photosynthesis and stomatal and total equivalent mesophyll resistances to CO2 transfer were measured in relation to irradiance, needle temperature, and tree water potential. Maximum rates of net photosynthesis were attained at 380 W m−2 irradiance, 20 °C needle temperature, and the highest tree water potential obtained, ca. −2.5 bars. Stomatal and total mesophyll resistances have a significant rate-limiting role when environmental conditions are less than optimum. Mesophyll resistance was larger than stomatal resistance under all environmental conditions.

EFFECTS OF GREENHOUSE CO2 ENRICHMENT ON THE YIELD AND PHOTOSYNTHETIC PHYSIOLOGY OF TOMATO PLANTS

1978 ◽  
Vol 58 (3) ◽  
pp. 801-817 ◽  
Author(s):  
PETER R. HICKLENTON ◽  
PETER A. JOLLIFFE
Keyword(s):  
Dark Respiration ◽  
Co2 Enrichment ◽  
Stomatal Resistance ◽  
Tomato Plants ◽  
Behavioral Indices ◽  
Respiration Rates ◽  
Growth Regime ◽  
Photosynthetic Physiology ◽  
Marketable Fruit ◽  
Mesophyll Resistance

Tomato crops were grown in greenhouses with and without CO2 enrichment to approximately 900 vpm. Plants grown under enhanced CO2 concentrations flowered earlier and produced 30% more marketable fruit than those grown in normal air. Measurements were conducted on CO2 and water vapor exchanges in apical and basal leaves under a range of irradiances and CO2 concentrations. Photosynthesis rates were higher in leaves from the enriched regime at test irradiances above 50 μE m−2 s−1 (400–700 nm). Increasing test CO2 concentration enlarged that difference, with the effect being most pronounced in apical leaves. Mesophyll resistance to CO2 assimilation was greater than stomatal resistance at all irradiances, and tended to be higher in basal leaves than in apical leaves of the CO2-enriched plants. Stomatal resistances were similar in apical and basal leaves from CO2-enriched plants. In unenriched plants, however, stomatal resistances were lower in apical than in basal leaves. CO2 compensation points were decreased in leaves developed under CO2 enrichment, but dark respiration rates were not significantly affected by growth regime. Behavioral indices of photosynthesis indicated that the efficiency of CO2 utilization was improved by growth in a CO2-enriched regime. Such fundamental changes in photosynthetic behavior suggest that the effects of CO2 enrichment on yield are not only due to increased growth in the presence of additional photosynthetic substrate. They also result from changes in the innate capacity of photosynthetic systems to utilize CO2.

Effects of pretreatment temperature on carbon dioxide exchange in alfalfa

1972 ◽  
Vol 50 (9) ◽  
pp. 1925-1930 ◽  
Author(s):  
C. J. Pearson ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Temperature Response ◽  
Day Length ◽  
Carbon Dioxide Exchange ◽  
Response Curves ◽  
Free Atmosphere ◽  
Pretreatment Temperature ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
The Relationship

The temperature response curves for net carbon dioxide exchange are described for plants of cultivars (cvs.) Vernal and Moapa alfalfa (Medicago sativa L.) grown at day/night temperatures of 30/25C and 20/15C, an irradiance of 25 nE cm−2 s−1 (400–700 nm), and a day length of 15.5 h. Net carbon dioxide intake (NCI) of the tops decreased with increasing temperature from 20 mg dm−2 h−1 at 10C to 5 mg dm−2 h−1 at 40C. The nature of the NCI-temperature response curve was affected by pretreatment temperature, with NCI being lower at all temperatures except 10C after growth at 20/15C. Photorespiration, which reached its maximum value at a higher temperature (20–30C) than that required for maximum NCI, accounted for 22% of the gross carbon dioxide intake (net carbon dioxide exchange in an oxygen-free atmosphere) at 10C and 55% at 40C. Pretreatment affected the relationship between net carbon dioxide output (NCO) and temperature, with NCO being higher at 10C but lower at 30C after growth at 20/15C as compared to 30/25C.

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